Cinder Block (CMU) Offset Smoker

by jason_5hundy in Outside > Fire

163157 Views, 380 Favorites, 0 Comments

Cinder Block (CMU) Offset Smoker

001 - Cover Photo.jpg

For a small fraction the price of a heavy steel smoker, you can setup a large capacity cinder block version. Not only will it be cheaper it will be better insulated. Follow the instructions attached for a very effective, efficient and not bad looking unit.

Design & Dimension

3D_2.PNG
3D_1.PNG
3D_4.PNG
3D_3.PNG

Review design dimensions.

Clear Area

20170520_105804.jpg

  1. Clear appropriate sized area with offsets as needed.
  2. Soften and level dirt or ad layer of sand.

Procure Cinder Blocks & Bricks

20170520_122159.jpg

  • Cinder Block: 8x8x16 (Qty. 60)
  • Cinder Block (1/2): 8x8x8 (Qty. 15)
  • Cinder Block (Caps): 8x2x16 (Qty. 16)
  • Clay Brick: 4.5x9x1.75 (Qty. 24)

Base Layers

20170520_132448.jpg

  1. Place base layer of cinder blocks and use level to confirm flatness.
  2. Alternate seem on each level.
  3. Eliminate all air gaps.

Complete Firebox

20170524_065716.jpg
20170524_065831.jpg

  1. Build firebox with rotated CMU bricks for air inlet and outlet as shown.

Complete Chimney Structure

20170524_065822.jpg
20170524_065723.jpg

  1. With a chisel, break a 1/2 brick into half again so that the chimney has an opening as shown in picture.
  2. Stack chimney to 3 blocks high for appropriate air draw.

Add Top Caps

20170626_182603.jpg
20170626_182627.jpg

  1. Place top caps on alternating seems from cinder blocks underneath. (Top caps will ad a flat surface for lids to seal better)

Lid Construction

20170626_170440.jpg
20170626_170700.jpg
20170626_173318.jpg
20170626_175013.jpg
20170626_175044.jpg

Lid Dimensions: 30.5" x 38" (Qty. 2)

  1. Cut plywood to dimensions.
  2. Procure Heat Shield Insulation (4 ft x 6 ft) and cut to same dimension as plywood.
  3. Using a staple gun, apply insulation to bottom side of wood.
  4. Fasten two lid pieces with hinges in middle and and handles.

Add Clay Bricks

20170629_130307.jpg

  1. Line the inner firebox with clay bricks for extra heat protection for the concrete blocks.

Rebar Grate Support

20170626_180243.jpg
20170626_181123.jpg
20170626_181216.jpg

  1. Measure off alignment for rebar supports. (3 places)
  2. Using a 1/2 inch concrete drill bit, drill holes through only one side of blocks.
  3. Insert 25" long, 3/8" rebar.
  4. Procure or cut, 3/4" X 13 ga. flattened expanded metal sheet to 22" x 53"
  5. Place expanded metal on top of rebar for a cook grate.

Fire Box Lid

20170626_183048.jpg
  1. Procure 29" x 31", 3/16" thick carbon steel plate.
  2. Drill and bolt in handles for easier removal (not shown)

3/16 steel plate is necessary for firebox as temperature here will be too extreme for thinner materials

How to Use

20170629_132932.jpg
20170629_141818.jpg
20170629_172025.jpg
Temp.jpg
Food 1.jpg

Now you're ready to test it out!

  • Use a left over block as a damper for your incoming fire vent. Slide back and forth to adjust heat.
  • Leave stack vent open at all times.
  • Add another expanded metal grate over the fire-pit if you would like the option to grill over the fire. (Good for tri-tip and chicken)

(This specific pit has about a 20 degree difference from one side to the other....which is actually very impressive.)